This invention relates to framing for supporting the steel panels of steel clad doors and to steel clad doors embodying such frames. More particularly, the invention is directed to such a frame which is extremely strong yet can be produced at very low cost.
Conventionally the frames of steel clad doors are frames which define the perimeter of the door and are formed of lengths of solid wood assembled into a rectangular frame. These frames support the steel cladding with the interior of the frames being filled with insulation or the like.
Not only has wood become much more expensive but it is also subject to warping or twisting so that substitutes for wood have been sought with the result that it has been proposed that the wood frame members of frames for steel clad doors be replaced by like members of composite material as described in laid open Canadian Application Serial No. 2,210,124, laid open Jan. 10, 1998.
The present invention resides in providing an improved frame structure which will have increased strength and rigidity over previous frames and will provide an increased area of support for the steel cladding yet will be extremely economical to produce.
According to the invention, there is provided a frame structure for a steel clad door which is formed from molded composite material in which at least the jamb members of the frame are formed as channels the side walls of which provide support for the steel cladding over the height of the walls. Further, according to the invention, the interiors of the jamb channels are provided with integrally molded bracing which extends between the channel walls.
According to the preferred form of the invention, the jamb channels have grooves in their outer bottom faces adjacent each side thereof, such grooves being adapted to receive the inturned edges of the steel cladding to secure the cladding to the frame.
Further, according to the preferred form of the invention, the header and sill of the frame also constitute channels of composite material.
Again, according to a preferred embodiment of the invention, the jambs of the frames are closed at their ends with the ends being notched to form seats to receive the header and sill members.
The composite material according to the invention for use in molding the members of the frame comprise particulate material bound together with a thermoplastic binder. More particularly, according to a preferred form of the invention, the composite material comprises a mixture of wood and waste particles bound together by a thermoplastic olefin. A particular preferred composition comprising approximately 30% thermoplastic olefins which preferably are recycled thermoplastic olefins, 30% wood particles and 40% waste particles including such things, for example, as fly ash, kiln dust, sand, or particles of glass, rubber, metal, peanut shells, cloth etc.